| Kojic acid has strong inhibitory effect on bacteria and belongs to natural preservative.Kojic acid has many advantages,such as not easy to be used by bacteria,wide bacteriostatic spectrum,good bacteriostatic effect and so on,so it has great application potential in food processing.In this study,kojic acid was applied to the preservation of cold fresh duck meat,the quality of cold fresh duck meat during storage was studied,the effect of kojic acid on the quality and microbial diversity of cold fresh duck meat was clarified,and the dominant spoilage bacteria in cold fresh duck meat were screened.The spoilage ability of different spoilage strains and the effect of kojic acid treatment on the ability of spoilage were analyzed.In order to provide theoretical support for the application of kojic acid in cold fresh duck meat,the bacteriostasis mechanism of kojic acid on spoilage microorganisms in cold fresh duck meat was further studied through the evaluation of bacteriostasis effect,the effect on cell membrane of spoilage bacteria and the effect of intracellular substances on the membrane of spoilage bacteria.You can see the main findings are as follows:The changes of cold fresh duck meat during storage was studied.With sensory evaluation,total colony total and TVB-N as the test index,0.1%,0.4%and 0.8%kojic acid were used as the treatment concentration.The effect of kojic acid on the quality of cold fresh duck during storage showed that kojic acid treatment could reduce the total colony of cold fresh duck meat during storage.The increase of number and TVB-N value slowed down the score of sensory evaluation,and improved the odor and color of duck meat in the storage process.The shelf life of cold fresh duck meat could be extended by about 4 d.The analysis of bacterial diversity in cold fresh duck meat showed that the abundance of bacteria in cold fresh ducks was rich,and Pseudomonas,Acinetobacter and Bacilli were the highest in fresh duck meat.After 6d storage,the diversity of the samples in the control group decreased,the species form was single,and the abundance of Pseudomonas was over 95%,and 0.8%The abundance of Pseudomonas kojic acid in the sample was 14%,compared with the control group the abundance of 95%,nearly 7 times lower.Compared with the control group,after 6 d storage,the growth of dominant spoilage bacteria in the cold fresh duck meat treated with kojic acid was obviously inhibited,and the species of microbes were also rich,from 4 to 11 of the control group.Pseudomonas,Aeromonas and Brochothrix thermosphacta sp.were isolated,purified,identified and preserved from cold fresh duck meat as the tested strains.Salmonella was used as the control strain.The changes of colony growth,sensory score and TVB-N value of the cold fresh duck meat after the infection were analyzed and detected.As well as the effect of trinic acid on the quality evaluation index of cold fresh duck meat after infection,the evaluation of the rot ability of the cold fresh duck meat was carried out by the tested bacteria.The results showed that the 4 strains of the tested strains showed different corrosion characteristics,the control strain,Salmonella,had strong corruption ability and the speed of proliferation in duck meat and Pseudomonas.Similar to Brochothrix thermosphacta,the amount of microbes in meat is acceptable at 4 d storage,and the yield factor of TVB-N is2.64×10-7 mgTVBN/CFU,second only to 2.88×10-7 mgTVBN/CFU of Pseudomonas aeruginosa,far higher than that of Aeromonas and Brochothrix thermosphacta;the yield factor of TVB-N in the test group of the acid treatment group is from high to low.Salmonella>Pseudomonas>Brochothrix thermosphacta>Aeromonas,and Aeromonas are most sensitive to the action of kojic acid,which are reduced from2.88×10-7 mgTVBN/CFU and 2.35×10-7 mgTVBN/CFU to 1.36×10-7 mgTVBN/CFU and 0.84×10-7 mgTVBN/CFU,which are nearly three times lower.Study on antibacterial activity of kojic acid evaluation based on inhibition of spoilage microorganisms,to spoilage bacteria the minimal inhibitory concentration,antibacterial effects and spoilage bacteria growth curve as the indexes,the results showed that:4 strains of bacteria sensitivity to kojic acid were Brochothrix,Aeromonas,Pseudomonas and Salmonella.The most The low inhibitory concentration was 500,1000,1000 and 2000 ug/mL,respectively.The bacteriostasis test showed that the diameter of the bacteriostasis circle of the 4 strains increased with the increase of concentration,and the results of the growth curve showed that the tartaric acid increased the delay period of the strain and delayed the arrival of the logarithmic growth period,and the high concentration of kojic acid could be complete.Inhibit the growth of the strain.The effects of kojic acid on the cell membrane of spoilage bacteria was studied through the hydrophobicity of the cell membrane of the strain treated by kojic acid was increased by 1-2 times by the surface hydrophobicity,cell membrane permeability,the leakage of intracellular Ca2+,K+,Mg2+,cell membrane protein and scanning electron microscope.The permeability of the membrane,destroying the ions in and out of the cell membrane,resulting in a large amount of Ca2+,K+and Mg2+ions in the cell.At the same time,it prevented the synthesis of macromolecular proteins and promoted the decomposition of small proteins.Kojic acid had obvious damage to the cell membrane,the cell was distorted and deformed,the surface was badly damaged,and the holes were increased.At the same time,there is a phenomenon of cell content overflow and aggregation.In the study of the effect of the intracellular substance of the bacteria in the bacteria,the experimental results showed that the treatment of the strains of respiratory chain dehydrogenase,beta galactosidase,alkaline phosphatase,the bacterial protein and the DNA analysis showed that the treatment of kojic acid seriously affected the activity of the intracellular enzyme,which resulted in the serious destruction of the exhalation chain dehydrogenase,and the beta galactose.The content of glucosidase and alkaline phosphatase increased;after the treatment of the acid,the large molecular bands of the mycelium protein were scarce and the small molecular bands disappeared.It showed that Kojic acid could obstruct the synthesis of protein and accelerate the decomposition of small molecular protein by interfering with the metabolism of protein.The results showed that kojic acid treatment could destroy the structure and normal synthesis of DNA and inhibit the growth and reproduction of spoilage bacteria. |
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